Requirement Engineering for Dependable Systems

Requirements engineering for dependable systems Tutorial Joint Meeting of DC/Baltimore SIGAda Chapter DC Chapter of ACM 11 October 2005 Dr. William Bail [email_address] The MITRE Corporation The authors’ affiliation with The MITRE Corporation is provided for identification purposes only, and is not intended to convey or imply MITRE's concurrence with, or support for, the positions, opinions or view points expressed by these authors.

Agenda ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

What we will cover ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Focus is on dependability ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Some aspects of reliance ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Dependability ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Laprie Dependability Tree Avižienis, Algirdas, Jean-Claude Laprie, and Brian Randell. “Fundamental Concepts of Computer System Dependability”. IARP/IEEE-RAS Workshop on Robot Dependability: Technological Challenge of Dependable Robots on Human Environments . May 21-22, 2001

Dependability attributes (page 1 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Dependability attributes (page 2 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Information Assurance ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Department of Defense. Information Assurance - DoD Directive.8500.1. Oct 2002. as previously discussed

Acceptability ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

What are requirements ? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Analysis of definition ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Just because something is a requirement, does not mean that it is a requirement Huh?

Could you repeat that? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Just because something is a requirement, does not mean that it is a requirement “ You get what you spec, not what you expect”

[object Object],[object Object],[object Object],[object Object],[object Object],IEEE Std 830-1998 System

Levels of systems ,[object Object],[object Object],System

Context of requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Component A Requirements Output Input

Major categories of requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Types of behavioral requirements (1 of 3) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Types of behavioral requirements (2 of 3) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Types of behavioral requirements (3 of 3) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Characteristics of behavioral requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Quality-of-construction requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Programmatic (contractual) requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Implementation requirements (1 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Implementation requirements (2 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Developing requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Decision points for requirements definition ,[object Object],Decision Process SW Reqs SW Reqs SW Reqs SW Reqs System Dsn System design Software design Decision Process Capabilities Set A Capabilities Set C System Reqs System Reqs System Reqs System Reqs System Dsn System Dsn Decision Process System Concept Set A Decision Process Capabilities Set B System Concept Set C Decision Process Mission Needs System Concept Set B

SW requirements analysis ,[object Object],[object Object],[object Object],[object Object],[object Object],Draft SRSs “ Final” SRSs Final SCIs SW Reqs Anl SW Dsn SW Impl SW Test Software Engineering Systems Engineering Sys Reqs Anl Sys Dsn Skipping SRA is very risky

SW requirements analysis techniques ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

When requirements are defined ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Requirements quality factors ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Description of quality factors (page 1 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Description of quality factors (page 2 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Common pitfalls ,[object Object],[object Object],[object Object],[object Object],[object Object]

Lack of prioritization of requirements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Over-specified / over-constrained / unbounded ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Volatile and late-defined requirements (1 of 4) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Volatile and late-defined requirements (2 of 4) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Volatile and late-defined requirements (3 of 4) ,[object Object],[object Object],[object Object],[object Object],[object Object],Level of understanding of desired behavior Likelihood that requirement will change External component dependencies Internal design dependencies Early definition low high high low complex simple weak strong Late definition

Volatile and late-defined requirements (4 of 4) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Unknown “physics” (1 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Unknown “physics” (2 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Mixing requirements and design (1 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Mixing requirements and design (2 of 2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Summary ,[object Object],[object Object],[object Object],[object Object]

End ,[object Object],Contact information Dr. William Bail [email_address] (202) 781-1945

References and Suggested Readings (1 of 3) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

References and Suggested Readings (2 of 3) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Requirement Engineering for Dependable Systems

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